Snap fire if they move, no penalty otherwise. Personally, I like Rhinos to avoid plasma and battle cannons.

Missile launchers are awfully expensive to risk only snap-firing, and staying still in an armored vehicle--particularly one as thin-skinned as a Rhino--kind of defeats the purpose for me. If it were up to me, I'd either have the ML-toting squad deploy in cover or terrain without a rhino, or move up the field quickly in a rhino and deploy with non-heavy weapons to improve their mobility and striking power. Just my opinion, though.

I would advise some vanguard veterans in your army they rock with heroic intervention. if you use the new imperial fist chapter tactics your bolt weapons will be able to re-roll to hit and I think wound

If you dont like war, who cares? life is short, and your probably gonna get eaten by Tyranids!